1. Field of the Invention
The present invention relates generally to an air passageway leading to an air injection valve for a gas turbine engine, to supply compressed air into a combustion chamber thereof to atomize fuel supplied to the engine.
2. Description of the Prior Art
The background of the present invention will be explained with respect to the arrangement of an air passageway communicating with an air injection valve installed in a gas turbine engine.
In a gas turbine engine, fuel supplied into a combustion chamber must be atomized through an air injection valve. Therefore, the air compressed by a compressor provided within the gas turbine engine is conducted to the air injection valve via an air passageway communicating between the compressor the air injection valve.
In prior-art gas turbine engines, however, a pipe located outside the engine defines conducting the air passageway to conduct the air compressed by the compressor to the air injection valve.
Accordingly, there exist a number of shortcomings. The basic problems are:
(1) Since the diameter of the pipe used as the air passageway is restricted due to the layout of other apparatus, it is impossible to provide a high-efficiency air supply passageway by increasing the inner diameter of the pipe to decrease the air flow velocity, that is, to reduce the kinetic energy loss within the pipe. As a result, in some cases, installation of an additional pressure source is necessary, especially when the engine is started.
(2) Since the air passageway is arranged outside the gas turbine engine, the air within the air passageway pipe is readily cooled, resulting in reduced combustion efficiency.
(3) Since the air is supplied to the air injection valve via an air inlet pipe and an air supply pipe, material and manufacturing cost for the pipes result in a higher cost for the gas turbine engine, including the additional cost of connectors and nuts used therewith.
The arrangement of a sample prior-art air passageway communicating with an air injection valve for a gas turbine engine will be described in more detail hereinafter with reference to the attached drawings under DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.